Formation of clean interfacial thin film solar cells

Abstract

A “three” chamber design multi-chamber cluster processing system which is used in the fabrication of a solar cell-comprising substrate. The processing system includes at least one PECVD processing chamber configured to deposit a p-doped layer, at least three PECVD processing chambers configured to deposit an i-layer, and at least one PECVD processing chamber configured to deposit an n-doped layer. The processing system also includes at least one central substrate transferring chamber which is typically located substantially equidistant from each of the PECVD processing chambers, and a transfer robot present in the central transferring chamber which is capable of paired transfer of substrates. An apparatus which provides a source of fluorine-comprising reactive species is in communication with each of said PECVD processing chambers.

1 . A method of fabricating a solar cell-comprising substrate, the method comprising:
 a) providing at least one PECVD processing chamber configured to deposit a p-doped layer, at least three PECVD processing chambers configured to deposit an i-layer, and at least one PECVD processing chamber configured to deposit an n-doped layer, wherein each p-doped layer is deposited in a processing chamber configured to deposit a p-doped layer, each i-doped layer is deposited in a processing chamber configured to deposit an i-doped layer, and each n-doped layer is deposited in a processing chamber configured to deposit an n-doped layer;   b) providing a central substrate transferring chamber which is used to transfer substrates between said PECVD processing chambers;   c) providing a substrate transferring robot having at least two sets of arms, where each set of arms is capable of transferring substrates, wherein said substrate transferring robot is located within said central substrate transferring chamber;   d) transferring solar cell substrates having a surface area of at least 1,000,000 mm 2  from PECVD processing chamber to PECVD processing chamber through said at least one central substrate transferring chamber using said substrate transferring robot;   e) depositing at least one p-doped layer, at least one i-layer, and at least one n-doped layer each solar cell-comprising substrate; and   e) periodically cleaning each of said processing chambers using a fluorine-comprising plasma to remove residue created during said depositing of a layer in said processing chamber.   
   
   
       2 . A method in accordance with  claim 1 , wherein said p-doped layer has a thickness ranging from about 120 Å to about 150 Å, and wherein a PECVD processing chamber in which said p-doped layer is deposited is cleaned when the thickness of residue formed on processing chamber surfaces ranges between about 5,000 Å and about 8,500 Å. 
   
   
       3 . A method in accordance with  claim 1 , wherein said i-layer has a thickness ranging from about 2,000 Å to about 3,000 Å, and wherein a PECVD processing chamber in which said i-layer is deposited is cleaned when the thickness of residue formed on processing chamber surfaces ranges between about 20,000 Å and about 30,000 Å. 
   
   
       4 . A method in accordance with  claim 1 , wherein said n-doped layer has a thickness ranging from about 200 Å to about 300 Å, and wherein a PECVD processing chamber in which said n-doped layer is deposited is cleaned when the thickness of residue formed on processing chamber surfaces ranges between about 10,000 Å and about 15,000 Å. 
   
   
       5 . A method in accordance with  claim 1 , wherein the number of single junction solar cell substrates processed per hour is at least 20. 
   
   
       6 . A method in accordance with  claim 5 , wherein said solar cell substrate comprises a multiple of solar cell junctions, and wherein the number of solar cell substrates produced per hour is equal to the number 20 divided by the number of junctions or a larger number. 
   
   
       7 . A method in accordance with  claim 1 , wherein an average total clean and seasoning time period per substrate, considering the cleaning and seasoning of all PECVD chambers is about 55 seconds or less. 
   
   
       8 . An apparatus used to fabricate a solar-cell comprising substrate, the apparatus comprising:
 a) at least one PECVD processing chamber configured to deposit a p-doped layer, at least three PECVD processing chambers configured to deposit an i-layer, and at least one PECVD processing chamber configured to deposit an n-doped layer, wherein said PECVD processing chambers are each sized to process a substrate having a surface area of at least 1,000,000 mm 2 ;   b) a central substrate transferring chamber which is used to transfer substrates between said PECVD processing chambers;   c) a substrate transferring robot having at least two sets of arms, where each set of arms is capable of transferring substrates, wherein said substrate transferring robot is located within said central substrate transferring chamber; and   d) an apparatus which provides a source of fluorine-comprising reactive species which is in communication with each of said PECVD processing chambers recited in a).   
   
   
       9 . An apparatus in accordance with  claim 7 , wherein said transfer robot is capable of at least 15 paired transfers of substrates per hour. 
   
   
       10 . An apparatus in accordance with  claim 8 , wherein a mechanical throughput rate of substrates per hour within said apparatus is at least 20.